Rangelands are important component of renewable natural resources in Saudi
Arabia. They play an important role in maintaining livestock industry of the
country. However, these rangelands are currently overexploited by means of
grazing; firewood gathering, ecotourism and other human activities. Attention
should be given to rangelands for future generations. Rangeland conservation is
one of the most prominent practices to maintain renewable plant resources and
prevent land degradation, loss of vegetation and desertification.
The current study was conducted in Al-Ghada Reserve, Unaizah, located in
the center of Al- Qassim region (25 º – 26 º N, 43 º - 44 º E, altitude 630-724 m
asl.). Al-Ghada Reserve is one of the oldest protected areas and most famous
places frequently explored by residents of the Al-Qaseem region.
The main aim of the present study is to build a database of information on
vegetation cover through the following objectives:
1. Inventory of plant species in protected areas.
2. Delineate plant communities in the reserve.
3. Compare of the vegetation with previous studies of the region.
Vegetation attributes, namely density, frequency and coverage were measured
in fifteen locations. Within each location, six quadrats (each 10m×10m) were
distributed randomly to measure the vegetation attributes. Soil samples were
collected from each location at a depth of 30 cm for determining physical and
chemical properties.
A total of 72 plant species were recorded that belonging to belonging to 62
genera and 26 families. Thirty six species were perennials. These include
Haloxylon persicum, Tamarix nilotica, Calotropis procera and Deverra triradiata.
The rest of species (50%) were annuals. They included Schismus barbatus,
Anthemis deserti, Allium atroviolaceum, Malva parviflora, and Plantago boissieri.
Seventeen species were shrubs, representing 23.61% of the total species. These
include Haloxylon salicornicum, Scrophularia hypericifolia, Zygophyllum
migahidii. Fifty five species were herbaceous representing (76.39%) of total
observed species. They included Centropodia forskalii, Tripleurospermum
auriculatum, Monsonia nivea, and Rumex vesicarius.
The application of multivariate statistical analysis techniques in the terms of
classification (Cluster Analysis) and ordination (Deternded Correspondence
Analysis (DCA), and Canonical Correspondence Analysis (CCA)) were employed
to identify vegetation types and their relevance to the underlying environmental
gradients. Four vegetation groups were identified as follows: (1) Haloxylon
salicornicum - H. persicum - Moltikiopsis ciliata, (2) H. salicornicum – M. ciliata,
(3) H. salicornicum - Calligonum comosu - Stipagrostis plumosa, and (4) C.
comosum - Deverra triradiata.
The results of the CCA indicated that the cumulative variance explained by the
first three axes was 65.4%. According to these results, the vegetation distribution
in the study area was mainly affected by soil texture, CaCO3 content.
The study indicated that vegetation represents different stages of succession.
For example, Haloxylon persicum community represents climax, while the
presence of other species such as annuals would suggest a sign of degradation. The
study also indicates that protection increases the percentage of vegetation cover,
density and frequency dramatically for all plant species that control soil erosion by
wind and water.
There is evidence that species diversity has increased within protected area, a
promising sign that demonstrates the ability of plants to regenerate naturally if
given the opportunity to do so. Therefore, a management plan should be inserted to
conserve and maintain the biodiversity in the reserve.